# Causes and Precautionary Measures of Wheel Chewing Track of Bridge Type Crane

- Mar 01, 2018 -

Causes and Precautionary Measures of Wheel Chewing Track of Bridge Overhead Crane

During the operation, the crane wheel edge and track compress tightly, resulting in increased running resistance, causing the wheel edge and rail wear phenomenon known as gnawing track. This will result in a significant reduction in the useful life of the wheels and rails and, in severe cases, derailment of the cranes, causing accidents to equipment and persons, as well as damage to the track's fixed and floor beams(or embankments) to varying degrees. On the basis of practical experience, this paper discusses the reason and prevention measures of wheel gnawing rail.

1. The Reasons

There are many reasons for the wheel chewing rail, some of which are orbital problems, some of which are wheel problems, and some of which are caused by deformation of bridge frame.

(1) Wheel problem

① There are three kinds of chews caused by the inaccurate installation of wheels

A. The wheel has a large horizontal deviation.

The wheel is installed with a horizontal deviation not greater than L 1000(L is the measured length on the wheel), and the opposite direction of a pair of wheels on the same axis shall be opposite, otherwise the wheel must be gnawed.

B. Vertical wheel
Too much deviation. The center line of the end surface of the wheel forms an angle with the plumb line, and the wheel is in an inclined state. The vertical deviation of the wheel should not be much dry L 400, the wheel vertical deviation caused by the gnawing rail means the driving wheel, and not passive wheel.

C. Car wheel spacing, diagonal disparity and the two wheels in the same track are not straight linear, which can also cause the crane wheel to gnaw track.

Wheel processing error caused by gnawing rail. The diameter of two main moving wheels is not equal, the running speed of the wheels on both sides will be different, after driving a distance, causing the car body to go diagonally, there is lateral movement, the phenomenon of gnawing rail, which is especially obvious for the centralized driving mechanism.

(2) Orbital issues

Car track installation quality is poor, the track is not straight, inevitably cause gnawing track. If two tracks have large deviation in relative height, the crane will move laterally, so that the two adjacent rail surfaces on the same side of the rail are not in the same water plane. When the crane reaches the rail joint, the wheel will move laterally, and there will be the phenomenon of oil, water and ice on the rail surface. The horizontal bend of the track is too large. When the tolerance is beyond the span, the wheel rims must be rubbed with the side of the track.

(3) Bridge frame deformation
The deformation of the bridge frame will cause the wheel skew and the crane span change, so that the end beam horizontal bend, cause the wheel horizontal skew, the vertical deviation is too bad, cause the wheel gnawing rail.

(4) Excessive manufacturing errors in transmission systems
The gear gap of the drive system of the big car running mechanism is not equal, the shaft key is loose etc. For the running mechanism driven separately, when the motor speed difference is too large, the brake adjustment degree is different, it will also cause the vehicle to go diagonally.

2. The way to check the tracks

The main inspection methods of the crane chewing track are:
(1) It can be concluded that the crane chews the track by visual inspection that there are bright marks on the side of the rail, that serious marks are marked by hair scars or that there are bright spots on the inside of the wheel RIM.
(2) During the operation of the crane, during a short distance, the gap between the wheel rim and the rail is obviously changed, and the crane will be able to chew the track.
(3) When the crane is starting or braking, the body is tilted and twisted, which will cause the wheel to bite the rail.

3. Measures to prevent wheel chewing

For the centralized drive and the separate drive running mechanism, the method of preventing and improving the wheel gnawing rail of Crane should be different. Through careful inspection, carefully adjust, correct the wheel and track inaccurate installation, pay attention to drive the running mechanism on both sides of the motor, brake and reducer existing different step problems.

(1) Limit the ratio of bridge span L to wheel distance K. The crane operation allows a certain amount of free skew, that is to allow a certain distance between the wheel rim and the rail. The larger the distance, the less it will nag the track, and with the L K ratio, the larger the ratio, allowing the freedom of skew smaller, the more easy to bite the track. Therefore, the experience of small L K value shows that L K value is not more than 5 ~ 6 more advantageous.

(2) Centrally driven operating mechanisms, such as a total of four wheels, of which two are active wheels, which may be fitted with a cone tread(taper of 1:10) and with a large end of the cone mounted inward, with a convex roof track, where the lifting opportunity to automatically adjust the course of the operation after several swings reduces friction between the wheels.

(3) The wheel rim and track side are lubricated in order to reduce the friction resistance of the wheels.

(4) Check the bridge frame regularly and correct it in time so as to meet the technical requirements, otherwise the problem of gnawing rail can not be solved fundamentally.